Treatment of Irritable Bowel Syndrome

Abstract

A method of treating irritable bowel syndrome in a patient in need thereof by administering to said patient a pharmaceutically effective amount of tapentadol.

Claims

1. A method of treating irritable bowel syndrome in a patient in need thereof, said method comprising administering to said patient a pharmaceutically effective and physiologically acceptable amount of tapentadol.

2. A method according to claim 1, wherein the tapentadol is present in a medicament.

3. A method according to claim 2, wherein the medicament is solid.

4. A method according to claim 1, wherein the medicament is formulated for oral administration.

5. A method according to claim 2, wherein the medicament is a tablet.

6. A method according to claim 2, wherein the medicament is formulated for administration twice daily (bid).

7. A method according to claim 2, wherein the medicament contains tapentadol in an amount of 10 to 300 mg.

8. A method according to claim 1, wherein said patient is a mammal.

9. A method according to claim 1, wherein said patient is a human.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The following gives a brief description of the figures:

[0050] FIG. 1 shows the effects of tapentadol hydrochloride on the twitch contractions of the isolated guinea pig ileum. Tapentadol hydrochloride was applied cumulatively to electrically stimulated guinea pig ileum preparations. After the last application of tapentadol hydrochloride, naloxone (10.sup.−6 M) was added. Drug effects on the twitch reaction were calculated as percentage of pre-value and expressed as mean±s.e.m.

[0051] FIG. 2 shows the anti-nociceptive effect of tapentadol hydrochloride in mustard oil colitis, as measured as inhibition of the spontaneous pain score.

[0052] FIG. 3 shows the anti-allodynic effect of tapentadol hydrochloride in mustard oil colitis, as measured as inhibition of the referred allodynia.

[0053] FIG. 4 shows the anti-hyperalgesic effect of tapentadol hydrochloride in mustard oil colitis, as measured as inhibition of the referred hyperalgesia.

[0054] FIG. 5 shows the time course of the anti-allodynic effect of curative tapentadol hydrochloride in mustard oil colitis, as measured as inhibition of the referred allodynia.

[0055] FIG. 6 shows the time course of the anti-hyperalgesic effect of tapentadol hydrochloride in mustard oil colitis, as measured as inhibition of the referred hyperalgesia.

[0056] In the respective figures Veh represents Vehicle solution: 0.9% NaCl solution (Fresenius, Bad Homburg, FRG), PEG Veh represents Vehicle solution PEG 200 (Polyethylene glycol; molecular weight 200 g/mol).

DETAILED DESCRIPTION

[0057] The following examples serve for a further explanation of the invention but should not be construed as restrictive.

[0058] The studies presented below clearly show the inhibitory effects of tapentadol on ileum contractions and on visceral nociception, referred visceral hyperalgesia and allodynia. Thus, tapentadol addresses major symptoms of IBS, abnormal gastrointestinal (GI) motility and visceral hypersensitivity and referred pain.

EXAMPLES

1. Effects of Tapentadol on the Twitch Contractions of the Isolated Guinea Pig Ileum.

[0059] It was investigated whether tapentadol is able to modulate gastrointestinal motility. For this purpose, the responses to the compound were tested on electrically induced contractions of guinea pig ileum (so called Twitch reactions), which are known to be reduced e.g. by opioids (Paton, WDM. (1957) The action of morphine and related substances on contraction and on acetylcholine output of coaxially stimulated guinea-pig ileum. Br. J. Pharmacol. Chemother. 11: 119-127).

1.1 Experimental Animals

[0060] Male guinea pigs (PBW, Charles River, KiBlegg, FRG) weighing 250-350 g were used for the study. The animals were kept under standard housing conditions: light/dark rhythm (06.00-18.00 h light, 18.00-6.00 h dark); room temperature 22±2° C., rel. air humidity 55±5%; 15 air changes per hour, air movement <0,2 m/sec. The animals were given water and an exclusive diet of “Herilan RM 204” (Eggersmann Company, Rinteln/FRG) ad libitum. Before experimental preparation they were kept in groups of up to 5 animals in type IV Makrolon cages (Ebeco Company, Castrop-Rauxel, FRG). There were at least 4 days between delivery and test day.

1.2 Compounds

[0061] Tapentadol hydrochloride was dissolved in aqua bidest. Final concentrations in the organ bath ranged from 3.Math.10.sup.−8 to 10.sup.−5 M (cumulative drug application). As opioid antagonist naloxone (10.sup.−6 M) was used.

1.3 Experimental Method

[0062] A four-compartment organ bath (Dept. Biotechnology, Grunenthal GmbH) was employed with 20 ml acrylic glass compartments, organ supports and force transducers (F10 Force transducers, Type 375, HSE, FRG) for the determination of isometric contractions. The organ baths were filled and emptied by means of a semi-automatic dosing arrangement. The nutrient medium in the organ baths was kept at room temperature. In a nutrient storage chamber and in the organ baths the nutrient solution was gassed with carbogen through a frit from 30 min before commencement of the experiment.

[0063] The nutrient solution had the following composition:

TABLE-US-00001 NaCl 118.0 mM KCl 4.8 mM CaCl.sub.2•2H.sub.2O 1.3 mM KH.sub.2PO.sub.4 1.2 mM MgSO.sub.4•7H.sub.2O 1.2 mM NaHCO.sub.3 25.0 mM Glucose 11.0 mM Ascorbic acid 0.57 mM Na.sub.2-EDTA 0.03 mM (pH: 7.4-7.5)
Parameter: contraction force [g]

1.4 Experimental Performance

[0064] Guinea pigs were killed in CO.sub.2-atmosphere and the ileum was dissected free from adhering tissue, removed and suspended in the organ bath. After an incubation period of at least 30 min, transmural stimulation pulses were delivered with a duration of 1 ms and an amplitude of 180 mA at 0.03 Hz (Stimulator A310, WPI, FRG) and isometric contractions (Twitch reactions) were recorded. The preparations were pre-tensioned with 1 g. During the equilibration period of at least 30 min, the pre-tensioning was corrected to a constant level (approximately 1 g) and the nutrient was changed twice.

[0065] After registration of the pre-value, tapentadol hydrochloride was added to the organ bath in cumulative concentration steps as indicated. The exposition time for each cumulative concentration was 6 min. After the last application of the test compound, the opioid-antagonist naloxone (10.sup.−6M) was added without previous wash out of the test compound.

1.5 Evaluation

[0066] Data were calculated as the mean stimulated contraction force during the period of 4 to 6 min. p. appl. and expressed as percentage of the pre-value. The mean contraction force in a period of 2 min before drug application was taken as pre-value. All results were expressed as means±s.e.m. of 4 single experiments. For determination of 1050 values, regression lines (y=f log x) were constructed and 1050 values with s.e.m. were calculated using a computer-assisted regression analysis program (Grünenthal GmbH). The reversal of the test compound's activity by the antagonist was expressed as the percentage of the effects of the combination of agonist and antagonist referred to the effects of the test compound alone in the highest concentration according to the following formula:

[00001]$\%\mathrm{reversal}=100\%-\frac{\max .{\mathrm{effect}}_{\mathrm{test}\mathrm{compound}+\mathrm{antagonist}}}{\max .{\mathrm{effect}}_{\mathrm{test}\mathrm{compound}}}\times 100\%$

with max. effect being: [0067] 100% - % reduction of pre-value of twitch reaction at highest dose of test compound.

1.6 Results

[0068] The compound reduced the electrically induced contractions of the isolated guinea pig ileum in a concentration dependent manner: The threshold concentration of the compound was about 10.sup.−7M and an IC.sub.50 value of 1.49±0.20 10.sup.−6 M was determined (see FIG. 1 and Table 1). With increasing concentrations of the compound up to 10.sup.−5 M, the twitch reactions were almost blocked (reduction down to 5.77±1.26% of pre-value). The inhibitory effect of the compound was reversed by 33.3% after addition of the opioid receptor antagonist naloxone (10.sup.−6 M).

TABLE-US-00002 TABLE 1 Effects of the compound on Twitch contractions of the guinea pig ileum IC.sub.50 Max. effect % reversal [10.sup.−6 M] [% pre-value] by naloxone tapentadol 1.49 ± 0.20 5.77 ± 1.26 33.3 hydrochloride

2. Effects of Tapentadol on Visceral Hyperalgesia

[0069] The effects of tapentadol hydrochloride on visceral hyperalgesia were studied, which was induced by rectal administration of mustard oil in mice (according to Laird J M, Martinez-Caro L, Garcia-Nicas E, Cervero F. (2001) A new model of visceral pain and referred hyperalgesia in the mouse. Pain 92: 335-42). The typical visceral pain behaviour was quantified in three parameters: During the first minutes after mustard oil administration spontaneous visceral pain behaviour occurs. Following this period of spontaneous pain, referred allodynia and hyperalgesia can be quantified by means of von Frey filaments of different strength stimulating the abdomen of the mice.

2.1 Animals

[0070] Male NMRI mice (28-38 g body weight) from a commercial breeder (Iffa Credo, France) were used. The animals were housed under standardized conditions: light/dark cycle (06.00-18.00 h light, 18.00-06.00 h dark), room temperature 20-24° C., relative air humidity 35-70%, 15 air changes per hour, air movement <0,2 m/sec, tap water and standard diet ad libitum, macrolon type 4 cages with maximally 30 animals per cage. There were at least 5 days between delivery and start of the experiment.

2.2 Compounds

[0071] Tapentadol hydrochloride was dissolved in vehicle solution and injected intra-venously. [0072] Doses: 2.15/ 4.64/ 10.0 mg/kg i.v. (prophylactic) 10.0/ 21.5/ 31.6 mg/kg i.v. (curative) [0073] Administration volume: 10 ml/kg

[0074] Vehicle solution: 0.9% NaCl solution (Fresenius, Bad Homburg, FRG)

[0075] Mustard oil was dissolved in vehicle solution and administered intra-rectally Dose: 50 μl of a 3.5 Vol-% solution per animal [0076] Vehicle solution: PEG 200

2.3 Experimental Preparation

2.3.1 Induction of Colitis

[0077] Animals were habituated to the test conditions for 20-30 min and stimulated with von Frey filaments onto the abdominal wall. 10 stimulations with von Frey filaments of 1, 4, 8, 16, and 32 mN were applied in ascending order (i.e. 10×1 mN, 10×4 mN, etc.). Animals with more than 25 positive reactions during this phase were excluded. Vaseline was applied in the perianal area to avoid the stimulation of somatic areas with the irritant chemical. Colitis was induced by rectal administration of 50 pl mustard oil (3.5%). Control animals were treated with vehicle (50 μl PEG200). Group sizes were n =7 for all experiments.

2.3.2 Prophylactic Treatment

[0078] Tapentadol hydrochloride or vehicle was given intravenously (i.v.) 5 min before mustard oil. Seven animals were tested per group. The following parameters were counted:

2-12 min after Mustard Oil: [0079] 1. Spontaneous pain score: counting and scoring of visceral pain behaviours (Score 1-2, 1=licking of abdominal wall, 2=stretching, squashing, mounting, backward-movement or contraction of the flank muscles).
20-40 min after Mustard Oil [0080] 2. Referred allodynia (number of reactions): counting of withdrawal reactions against 10 stimulations with a 1 mN von Frey filament. [0081] 3. Referred hyperalgesia (referred pain score): counting and scoring of withdrawal reactions against 10 stimulations with a 16 mN von Frey filament (Score 1-3, 1=lifting of abdomen, licking, movement, 2=extrusion or flinching of hind paws, slight jumping, strong licking, 3=strong jumping, vocalisation).

2.3.3 Curative Treatment

[0082] Tapentadol hydrochloride or vehicle was given intravenously (i.v.) 4 hours after mustard oil. Seven animals were tested per group. The following parameters were counted 10 minutes before and at different time points after administration of the test compound or vehicle: [0083] 1. Referred allodynia (number of reactions): counting of withdrawal reactions against 10 stimulations with a 1 mN von Frey filament. [0084] 2. Referred hyperalgesia (referred pain score): counting and scoring of withdrawal reactions against 10 stimulations with a 16 mN von Frey filament (Score 1-3, 1=lifting of abdomen, licking, movement, 2=extrusion or flinching of hind paws, slight jumping, strong licking, 3=strong jumping, vocalisation).
Percent of maximal possible effect (% MPE) was calculated for each animal based on the baseline taken 10 min before administration of compound or vehicle.

2.4 Statistical Analysis

[0085] Significance was calculated by paired T-test (* 0.05≥p>0.01; ** 0.01≥p>0.001; *** p≤0.001. ED.sub.50 values and 95% confidence intervals were calculated by linear regression.

2.5 Results

2.5.1 Mustard Oil Colitis, Prophylactic Treatment

[0086] Tapentadol hydrochloride was tested in doses of 2.15/ 4.64 and 10.0 mg/kg i.v. It showed a dose dependent inhibition of all three visceral pain parameters. Spontaneous visceral pain behaviour (FIG. 2), referred allodynia (FIG. 3) and referred hyperalgesia (FIG. 4) were inhibited with ED50-values (95% confidence intervals) of 1.47 (0.51-2.28)/3.75 (2.76-4.75)/and 3.93 (2.32-5.69) mg/kg i.v., respectively.

2.5.2 Mustard Oil Colitis, Curative Treatment

[0087] Curative administration of the compound in doses of 10.0/ 21.5 and 31.6 mg/kg i.v. after mustard oil showed a dose dependent inhibition of referred allodynia and referred hyperalgesia with ED50-values (95% confidence intervals) of 21.7 (19.3-25.0) and 16.3 (12.5-19.9) mg/kg i.v., respectively. The time course showed maximal efficacy 20 min after administration and duration of action of 1 to 2 h in the referred allodynia (FIG. 5) and of more than 2 h in the referred hyperalgesia (FIG. 6). Almost full efficacy was reached at a dose of 31.6 mg/kg, i.v.